Taraxacum officinale

Taraxacum officinale grows from a (generally unbranched) taproot and produces several hollow, leafless flower stems, typically tall, but occasionally reaching up to tall. The stems can be tinted purplish, are upright or lax, and produce flower heads that are held as tall or taller than the foliage. The foliage may be upright-growing or horizontally spreading; the leaves have petioles that are either unwinged or narrowly winged. The stems can be glabrous or sparsely covered with short hairs. Plants have milky latex, and the leaves are all basal; each flowering stem lacks bracts and has one single flower head. The yellow flower heads lack receptacle bracts, and all the flowers, which are called florets, are ligulate and bisexual. In many lineages, the seeds are mostly produced by apomixis, The leaves are long and wide, and they are oblanceolate, oblong, or obovate in shape, with the bases gradually narrowing to the petiole. The leaf margins are typically shallowly lobed to deeply lobed and often lacerate or toothed with sharp or dull teeth. range in colour from olive-green or olive-brown to straw-coloured or greyish; they are oblanceoloid in shape and long, with slender beaks. The fruit have 4 to 12 ribs that have sharp edges. The silky pappi, which form the parachutes, are white to silver-white in colour and around 6 mm wide. Plants typically have 24 or 40 pairs of chromosomes, while some have 16 or 32 pairs. Rudenskaya et al. (1998) found that taraxalisin hydrolyzes a chromogenic peptide substrate Glp-Ala-Ala-Leu-pNA optimally at pH 8.0. Maximal activity of the proteinase in the roots is attained in April, at the beginning of plant development after the winter period. ==Taxonomy==

Carl Linnaeus named the species Leontodon taraxacum in 1753. The current genus name Taraxacum derives possibly from the Arabic Tharakhchakon, and Rothmaler's Flora of Germany accepts roughly 70 microspecies. European dandelions Taraxacum officinale L. (dandelion) is a vigorous weed in Europe with diploid sexual populations in the southern regions and partially overlapping populations of diploid sexuals and triploid or tetraploid apomicts in the central and northern regions. , Slovenia These European dandelions can be divided into two groups. The first group reproduces sexually, as do most seed plants. This group consists of dandelions that have a diploid set of chromosomes, and are sexually self-incompatible. Sexual reproduction involves a reduction of the somatic chromosome number by meiosis followed by a restoration of the somatic chromosome number by fertilisation. Diploid dandelions have eight pairs of chromosomes, and meiosis is regular with normal pairing of homologous chromosomes at the metaphase I stage of meiosis. The second group consists of polyploid (mostly triploid) apomicts, meaning that both a viable embryo as well as a functional endosperm is formed without prior fertilisation. In contrast to the sexual diploids, the pairing of chromosomes at metaphase I in triploid apomicts is strongly reduced. However pairing is still sufficient to allow some recombination between homologous chromosomes. Some authorities recognise two subspecies of Taraxacum officinale, including: The Arabic term is possibly of Persian origin. Persian polymath Al-Razi used the word in relation to dandelions, chicory, and endives. Al-Razi wrote "the is like chicory, but more efficacious"; it is unclear exactly to which plant Al-Razi referred however. Gerard of Cremona, in translating Arabic to Latin around 1170, spelled it tarasacon. The Latin specific epithet officinale refers to the Latin word for 'medicinal' or 'of the apothecaries'. T. officinale has many English common names (some of which are no longer in use), lion's-tooth, cankerwort, milk-witch, yellow-gowan, Irish daisy, monks-head, priest's-crown and puff-ball; The balls of seed heads are called "clocks" in both British and American English or "blowballs". The common name dandelion comes from the French dent de lion, or "lion's tooth", in reference to the plant's jagged-edged leaves. ==Distribution and habitat==

Taraxacum officinale is native to Europe and Asia, and was originally imported to America as a food crop. It is now naturalised throughout North America (including all 50 states of the US and most Canadian provinces), The plant is coveted by collectors in regions where the plant is trickier to grow such as the tropics, where people would often resort to smuggling seeds from overseas. Conservation Taraxacum officinale was evaluated in 2013 by the IUCN as "Least Concern" due to a large and stable population. ==Ecology==

It is considered a noxious weed in some jurisdictions, and is considered to be a nuisance in residential and recreational lawns in North America. It is also an important weed in agriculture and causes significant economic damage because of its infestation in many crops worldwide. The dandelion is a common colonist of disturbed habitats, both from wind blown seeds and seed germination from the seed bank. When released, the seeds can be spread by the wind up to several hundred meters from their source. The seeds are also a common contaminant in crop and forage seeds. The plants are adaptable to most soils and the seeds are not dependent on cold temperatures before they will germinate but they need to be within the top of soil. T. officinale is food for the caterpillars of several Lepidoptera (butterflies and moths), such as the tortrix moth Celypha rufana. See also List of Lepidoptera that feed on dandelions. Even though dandelion pollen is of poor nutritional quality for honey bees, they readily consume it, and it can be an important source of nutritional diversity in heavily managed monocultures such as that of blueberries, or in early spring, as one of the first flowers to bloom. Honey bees have not been shown to lower their pollination activity on nearby fruit crops when foraging on dandelions. While not in bloom, this species is sometimes confused with others, such as Chondrilla juncea, that have similar basal rosettes of foliage. The dandelion thrives in conditions of elevated carbon dioxide, growing to a higher biomass and producing a larger number of viable seeds. Therefore, it is anticipated that the dandelion will become more competitive and widespread as atmospheric carbon dioxide levels increase. In one study, it ranked as the fourth most important pollen source, after willow, meadowsweet and blackberry. ==Uses==

Culinary The plant has several culinary uses: the flowers are used to make dandelion wine, Dandelions are harvested from the wild or grown on a small scale as a leaf vegetable. The leaves (called dandelion greens) can be eaten cooked or raw in various forms, such as in soup or salad. They are probably closest in character to mustard greens. Usually the young leaves and unopened buds are eaten raw in salads, while older leaves are cooked. Raw leaves have a slightly bitter taste. Dandelion salad is often accompanied with hard-boiled eggs. The leaves are high in vitamins A and C, as well as iron, phosphorus, and potassium. Dandelion flowers can be used to make dandelion wine, for which there are many recipes. It has also been used in a saison ale called Pissenlit (the French word for dandelion, literally meaning "wet the bed") made by Brasserie Fantôme in Belgium. Dandelion and burdock is a soft drink that has long been popular in the United Kingdom. Another recipe using the plant is dandelion flower jam. In Silesia and other parts of Poland and the world, dandelion flowers are used to make a honey substitute syrup with added lemon (so-called May-honey). Ground roasted dandelion root can be used as a non-caffeinated coffee substitute. have been well described. The leaves of the common dandelion have been used as a diuretic in traditional Chinese medicine for approximately 2,000 years, with other regions of the world using the plant in the same way; in French, a common name for T. officinale is pissenlit, 'a colourful description of its diuretic activity'. A study conducted in 2009 noted 'promising' results regarding these diuretic properties, but that further studies would need to be conducted into the plant's efficacy. Herbal medicine Dandelion has been used in traditional medicine in Europe, North America, and China. Research Since asexually-reproducing dandelions produce genetically identical offspring, they are often useful as subjects for scientific research. For example, dandelions are used in studies where genetic differences between subjects needs to be minimal. Education Because of its worldwide distribution, familiarity, and presence in a wide variety of folkloric traditions, the dandelion has been highlighted as a valuable tool for educators seeking to help children of varying cultural and ethnic backgrounds connect to science through ethnobotany. Folklore blowing on the seed head of a dandelion In folklore, blowing on the seed head of a dandelion is used as a method of divination to tell fate. Other Yellow dyes can be obtained from the flowers but little colour can be obtained from the roots of the plant. ==In culture==

Cultures worldwide tell stories about the dandelion and have culinary and medicinal uses for it. A Native American folktale tells the story of a golden haired girl who attracted the fancy of the South Wind. The South Wind was too lazy to pursue her, until one day he realised she had grown old and her hair had turned white. Supposedly, when the South Wind sighs over the loss of his chance to pursue the golden-haired girl, his breath sends the white-haired dandelion seeds scattering to propagate more golden-haired daughters. ==See also==